Pneumatic nailing hammer



June 3, 1947. H. J. ALTER PNEUMATIC NAILING HAMMER Filed May 4, 1944 4Sheets-Sheet l June 3, 1947. ALTER 2,421,474

PNEUMATIC MAILING HAMMER Filed my 4, 1944 4 Sheets-Sheet 2 j .i FI -5.

June 3, 1947. H. J. ALTER PNEUMATIC NAILING HAMMER Filed May 4, 1944 4Sheets-Sheet 3 INVEN TOR.

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Filed May 4, 1944 4 Sheets-Sheet 4 Patented June 3, 1947 PNEUMATICNAILING HAMMER Horace Jules Alter, North Hollywood, Calif. ApplicationMay 4, 1944, Serial No. 534,061

Claims.

This invention relates to a fluid pressure tool and in particular to apneumatic nailing hammer or nailing tool which has for its primaryobject the provision of a device for forming a nail, brad, or tack anddriving said nail, brad, or tack into wood, plastic, paper, cloth,metal, or other materials.

One object of this invention is the provision of a tool wherein a nailis cut, pointed and headed in a continuous operation by means of fluidpressure.

Another object of this invention is the provision of a tool which willhold the nail while it is eing driven into the materials that are to befastened together.

Another object of this invention is the provision of a light portabletool wherein all materials and means for forming and driving a nail areself-contained.

A further object of this invention is the provision of a tool whereby acontinuous supply of nails will be formed from a spool of wire by meansof fluid pressure, said nails being made and driven into the materialsto be fastened during a com- ;lcte cycle of operation of the tool.

A further object of this invention is to provide a tool for cutting,pointing, positioning, and driving wire nails by means of aself-contained mechanism utilizing fluid pressure to perform theoperations, said tool being capable of manufacturing nails of differentlength by adjusting means in said tool.

A still further object of this invention is to provide a tool, fluidpressure driven, whereby an assembly of parts and a fastening of parts,by means of nails, may be made a continuous and time saving operation byhaving materials for making a nail and apparatus and mechanism formaking and driving said nail all combined within a portable hand tool.

Still further objects of this invention are to provide a fluid pressureoperated nailing device which will eliminate the use of the hands tohold a nail while driving same into place by means of a hammer or malletand to provide a tool for making and driving nails, said tool notrequiring dexterity and strenuous exertion on the part of the operatorin driving nails, brads, Or tacks into materials which are to befastened together. Objects pertaining to economics of construction,speed of operation and promotion of safety by eliminating the hazardsincidental to the driving of nails by use of a hand held hammer willappear from the detailed description to follow.

With these and other objects in view, this invention consists in certainnew and novel features of construction, combination and arrangement ofparts and mechanisms which are to be more fully described and claimedhereinafter.

For a complete understanding of my invention, reference is to be had tothe following description and the accompanying sheets of drawingswherein I have illustrated a tool embodying my invention in itspreferred form and combination of parts.

Figure 1 is an elevation illustrating a pneumatic nailing hammerconstructed in accordance with my invention.

Figure 2 is a vertical sectional view illustrating the same and showingthe position of the parts at the start of a cycle of operation.

Figure 3 is a fragmentary vertical sectional view showing the cutters inthe process of cutting off a length of wire to form a nail point andhead.

Figure 4 is a fragmentary vertical sectional view showing the nail inthe process of being driven into the materials to be fastened.

Figure 5 is a sectional view taken on the line 55 of Figure 2.

Figure 6 is a sectional View 65 of Figure 2. 4

Figure 7 is a sectional view taken .on the 'l'! of Figure 2.

Figure 8 is a sectional view taken on the 8-8 of Figure 2.

Figure 9 is a sectional view taken on the 9-9 of Figure 2.

Referring in detail to the drawings, the pneumatic nailing hammercomprises a, cylinder body I constructed of metal, plastic or some othersuitable composition of materials and having a bore la adapted toreceive a piston 2. Said body is preferably of the shape as shown with ahandle to permit the tool to be readily grasped at the upper end but,may be modified by suitable arrangement of parts to eliminate the handleallowing the hammer to be grasped by the cylinder body or by means of aspade or T-shaped handle.

The upper end of the cylinder body is recessed and internally threadedto receive an externally threaded cylinder head nut 3, said nut servingas a closure for the upper end of the piston chamber and as a means forregulating the stroke of the piston whereby, the length of nail iscontrolled. The cylinder body is internally threaded at its lowerextremity and shouldered to receive and abut an externally threadedcutter cam body 5.

The grip handle 4 is preferably an integral part of the cylinder bodyand has an inlet fluid passage 8 internally threaded at 6 to receive afitting taken on the line line line

line

bore 9 and having a gear ll engageable with a rack I! to controlcommunication between inlet passages 8 and 8a and exhaust passages l8and la. It is to be understood that the valve may be modifiedto be of aslidable, poppet, ball, or diaphragm type by suitable rearrangement andconstruction of the handle without changing the scope of the inventionor its purpose.

Adjacent to the valve and operating within a recess out within thehandle is the valve trigger l2 pivotly mounted on pin l8 and having abore I3 for retaining atrigger spring [4 which contacts with the handle,said spring being retained in said handle by the bore I5.

The cylindrical shaped rotary valve has cut therein grooves I9 and l9awhich serve to connect respectively fluid inlet passages 8 and 8a andfluid exhaust passages I8 and 18a and communicate said passages with thecircumferential passages llb and 80 out within the walls of the cylinderbody and with the exhaust port 29.

Attached to the handle are arms 24 extending vertically and forming asupport for the spindle 25, said spindle being inserted through thespool 26 containing the wire for forming the nails. A plurality oftension spring 21 or a similar means of braking the spool, preventingsaid spool from turning freely and unwinding the wire, are insertedbetween the support arms and. the spool.

The wire for forming the nails passes through a gland nut 20 which isexternally threaded and has a central bore 2| and a counterbore 2la.Said nut has a shoulder 23 under which, is placed a gasket 23a abuttingthe cylinder head nut 3. The gland nut is recessed, at the lower face,to receive a packing 22 thus keeping the connection between the glandnut 20 andthe cylinder head nut 3 substantially fluid tight.

The cylinder head nut 3 is externally threaded to engage with thecylinder body I. Movement of the nut downward into the cylinder bodyshortens the length of piston stroke whereby the length of nail isshortened. Turning the nut outwardly lengthens the piston stroke wherebythe nail is lengthened. The cylinder head nut is internally threaded atthe upper end to receive gland nut 20 and has central bores 28 and 2811,(Figs. 1 and 5) the wire for forming the nail, extending through saidbores. A plurality of communicating ports 3a cut vertically through theside walls of the cylinder head nut and registering with thecircumferential passageway 8b communicates said passageway with thehollow chamber 30 cored out of the cylinder head nut (Fig. 5). Aplurality of ports 3b cored in the lower surface of said cylinder headnut lead from the hollow chamber to the interior of the cylinder.

The piston 2 (Fig. 3) slidably supported within the cylinder bore la hasa large central cavity 2a and a central bore 2b, the wire for formingthe nail extending through said bore. The lower surface of the pistonhead is counterbored around the central bore to receive a packing gland30, said gland substantially preventing leakage of fluid pressurethrough the central bore of the piston. The vertical face or skirt ofthe piston has cut therein a plurality of elongated slots 32' to allowvertical movement of the hammer head extension 34 and tongs 33 withinthe piston cavity and slots respectively.

The hammer head 4| is cylindrical in shape, the upper extremity 34 beingof reduced diameter and having a plurality of vertical grooves 36extending from the center. A central bore Ma extending throughout thelength of said hammer head allows the wire for forming the nail to passtherethrough. A plurality of tongs 33 preferably three or four in numberare rotatably pivoted in the slotted grooves 36 by means of pivots 31.

The upper ends of the tongs are rounded and bear on the shoulders 2c orthe shoulders 2d respectively (Fig. 3). The portions of the tongsforming the wire bore 39 and centrally located thereabout are serratedor knurled for effecting gripping of the tongs into the wire whenpressure is downwardly applied to the tong ends 38 by shoulders 2c.

The lower extremity of the hammer head (see Fig. 4) has an outwardlytapering 0r dovetail recess 40 centrally located about the wire bore toreceive the tapering shoulders 42a of the cutters 42.

The cutters 42 preferably three or four in number are slid-ablysupported within the central bore 43 of the cutter cam body 5. The upperextrem ities of the cutters form an outwardly taperin extension 42a ofreduced diameter which is engageable with the recess 40 of the hammerhead. The upper portion of the cutters has a rounded shoulder 42b ofmaximum diameter, said shoulder forming a slidable bearing for thecutters and the upper surface of said shoulder recessed to receive aring spring 46 for holding the cutter jaws outwardly against the cuttercam body walls. The upper extremity of the cutters has a centralinwardly tapering bore 35 leading to a spherical bore 3|, said sphericalbore receiving the cutter fulcrum 44.

The cutter fulcrum is spherical in shape, said fulcrum having a centralbore Ma, ends of said bore countersunk and the wire for forming the nailpassing through-said bore.

A central cavity extends vertically through the cutters from the fulcrumto the lower extremity of the cutters forming the interior of the cutterarms 42, said arms having vertical slots l] to slidably engage anvilcranks 53. The interior surfaces are tapered inwardly at the lowerextremity of the cutter arms to form the cutting edges 5|] while thelower exterior surfaces are tapered outwardly to form the cam surfaces49.

The cutter cam body 5 is preferably cylindrical in shape having a largecentral bore 43 in the upper portion extending to an outwardly taperingbore in the lower portion and thence tapering inwardly again at thelower extremity to form the cutting cam sliding surface 48. Said cuttercam body is externally threaded to receive and abut the cylinder body Ipositioning the cur.- ter cam bore 43 centrally about the hammer head4|. The cutter cam body is externally threaded at thelower extremity toengage with the anvil holder 52. A plurality of ports 5| permit the airtrapped within the cutter cam bore to escape to the surroundingatmosphere.

The anvil holder 52 is preferably cylindrical in shape and tapering atthe lower end to permit tool access to corners and close edges. Saidholder is internally threaded at the upper end to receive the cutter cambody 5 and has as an integral part or attached thereto a plurality ofbrackets 51 preferably three or four in number equally spaced about thecentral bore of the anvil holder, said brackets forming a support for aplurality of anvils 59 by means of the pivot pins 54. The lowerextremity of the anvil holder is cored to receive a cylindrical housingor bushing 54, said bushing forming a supporting means for thepositioning arms 55.

The upper extremity of the anvil holder 52 has a cam surface 58 (Fig. 4)which mates and aligns with the cam surface 48 of the cutter cam body 5,said cam surface providing a sliding means for the cutters. holder isknurled to permit better gripping of the anvil holder.

The anvils 59 preferably three or four in number are rotatably supportedin the anvil holder brackets 51 and are retained in an upright positionby means of the anvil springs 60. The anvil segments 6| form a platenhavinga central bore,

62 (Fig. 3) the perimeter of said here being serrated to form a wiregripping means. -The upper surface of said platen has a counter-bore 63for forming the nail head. A plurality of bell cranks 53 extend upwardfromthe anvil segments forming levers and cams against which the cuttersare in slidable contact.

The positioning arms .55 preferably three or four in number, are mountedin the positioning arm holder 54 by means of pivots 68 and are retainedin an upright position by springs 65. The positioning arm holder has aplurality of vertical slots 56 equal to the number of arms, said armsfolding downward into said slots when the cutters move downward past thepositioning arms. The arms are tapered downwardly along the uppersurface.

Although the foregoing description is of a detailed character. tocompletely set forth the invention, it is to be understood that thespecific terminology is'not intended to be restrictive or confiningsince it is to be understood that rearrangement of parts andmodification of structural details may be made without departing fromthe scope or purpose of the invention as herein claimed.

In explaining the operation of this invention, let it be assumed that aspool of wire has been inserted between the forked arms 24 and a lengthof wire has been threaded through the central bores of the pneumaticnailing hammer down to the cutting edges 50. Let it also be assumed,that the cylinder head nut 3 has been adjusted to cut a nail of a givenlength and that the valve trigger I2 and valve In are in the closedposition shown in Figure 1. The piston occupies the position at the topof the cylinder or beginning of its stroke. At this time, pressure istransmitted from the inlet fluid pressure duct 8 through the valvepassage l9a, through the passage i8 and the annular groove 80 to thebottom of the piston chamber la thereb exerting pressure on the bottomof piston 2 holding it at the upperend of the cylinder.

Holding pressure escaping between the piston and cylinder wallstowardthe top of the piston, passes out through the ports 3b into thehollow chamber of the cylinder head nut, through the annular groove 8bto the passage 8a and exhaust- The outer circumference of the supply orholding pressure to the bottom of thepiston and admitting live pressurethrough passage Sa, annular groove 8b and into the cylinder head nutchamber 3a. The full force of the pressure building up behind the pistonby flow through ports 3b causes the piston to move downward thus forcingthe piston shoulders against the rounded shoulders 38 of the tongs 33.Further downward movement of the piston causes rotation of the tongsabout the pivots 31 forcing the serrated jaws 39 into the wire in agripping motion.

The continued building up of pressure moves the piston downward forcingthe hammer head assembly consisting of tongs 33 and hammer head 4| tomove downward in the cylinder bore I a. Since the tongs 33 have grippedthe wire in the serrated jaws 39, the wire is' pulled along downwardthrough the central bores 28 and 2| of the cylinder head nut and glandnut respectively and pushed on downward past the cutting edges 50.

The piston and hammer head assembly continue to move downward until theinner face of hammer head dovetail recess 48 contacts the taperingcutter shoulders 42a thus forcing the cutters downward. The piston,hammer head assembly, and cutters continue to move downward unde fluidpressure pushing the wire on downward and into the central bore 62 ofthe anvils. The movement forces the cutters 42, which are held againstthe walls of the cutter cam body 5 by action of the spring 46, to slidealong the bore 43 to the cutter cam body sliding surfaces 48. Downwardmovement along th surface 48 and 58 forces the cutters 42 to rotateabout the cutter fulcrum 44 bringing the cutting edges 50 (see Fig. 3),together and shearing off a length of wire at the same time forming anew nail point on the wire immediately above the sheared section. It maybe seen that the length of nail cut may be adjusted by lengthening orshortening the piston stroke. Moving the cylinder head nut 3 upward ordownward within the threaded cylinder body I will determine the lengthof the stroke of the piston, hammer head assembly and cutters.

At the same time that the cutters are closed, the upper extensions 42aare forced outward and locked in the recess 40 provided in the hammerhead 4|. The hammer head and cutters are then looked together as a unitand move in unison with the piston.

During the downward stroke, a length of wire has been pushed past thecutters 42 and through the central bore 62 of the anvils 59 and isretained there by the anvil platens 6| under pressure of the springs 60.There is then a length of wire sufiicient to make a nail retained in theanvils, with a short length of wire 66 extending above the anvil recess63 (see Fig. 3).

Further downward movement of thepiston, hammer head assembly and cutterunits rotate the anvil cranks 53 outwardly about the pivots 64 causingthe anvils to firmly grip the length of wire in the bore 62 thereby,preventing further movement of the wire. The continued downward movementof said units under the fluid pressure, causes the closed cutter face,adjacent to the edges 50, to exert pressure on the short length of wireextending above the anvil platens. Under the pressure, applied by thecutter face, plastic flow of the wire material results, causing theexcess of wire material 66 above the anvil platen 6| to upset and flowinto the recess 63. A nail head is thus formed.

Still further downward movement of the said units causes the cuttersface to contact the face of the anvil platens, at the same time aligningthe vertical slots 41 of the cutters with the anvil cranks 53, whereby,the anvils are forced to rotate about the pivots 64 causing the anvilcranks to enter into the vertical slots 41 thereby releasing the nail 61from the gripping bore 62 (see Fig. 4) The downward motion of thepiston, hammer head assembly and cutters pushes the nail into thepositioning arms 55 holding the nail in appropriate position fordriving. I

Continued movement of said units forces the nail GI-into thematerials tobe nailed together by action of the cutters face on the nail head. Thecutters moving down and past the positioning arms 55 causes them torotate about the pivots 68 and forcing them downward and outward intothe recesses 56. The units continue to move downward until the nail isdriven home, thus completing that portion of the cycle ihcidental tomaking and driving a nail.

As the trigger is released, under spring pressure, it actuates therotary valve causing passage 8a to communicate with I81; and passage 8to communicate with 3 thereby cutting off the supply of fluid pressureto the top of the piston and admitting live pressure fluid throughpassage 18' and annular groove 80 to the bottom of the piston thereby,forcing the piston upward. The piston moves upward until the shoulder 2dcontacts the underside of the tong ends 38 thereby causing the tongs torotate upward and outward about the pivots 31 thus releasing the wire.The shoulder 2d abutting the tong ends 38 causes the piston, hammer headassembly and cutters to move upward in unison pushing the wire backwardand upward by means of the closed cutter jaws. As the cutters moveupward past the positioning arms 55, said arms rotate inwardly andupwardly under action of the spring 65 causing the arms to assume theirinitial position.

Further upward movement of the assembly past the anvils allows theanvils to rotate about the pivots, upwardly and inwardly, under actionof the springs 60 whereby, the anvils are caused to assume their initialclosed position.

Still further upward movement of the units draws the cutters upwarduntil the jaws are rotated outwardly about the fulcrum 44, unde actionof the ring spring 46, into the tapered bore of the cutter cam body 5.This releases the wire which is no longer pushed upward by the closedcutters but, is held stationary by friction of the various glands andpackings as well as the wire spool brake.

Continued upward movement and the outwardly opening movement of thecutterareleases outwardly tapering extensions 42a. of the cutters Havingthus described my invention and its operation, what I claim is:

1. A fluid pressure operated tool for making and driving fastenerscomprising a casing formed with a bore; means for holding a supply ofwire on the casing; a pressure operated plunger reciprocable in thebore;means' engageable with the plunger for drawing wire from the supplyand feeding it forwardly; a hammer, operated by the plunger; cutters,slidable within the casing and operated by the hammer, for severing astrip of wire; meansfor pivoting the cutters during their slidingmovement to cause them to point the leading end of each successive stripof wire; and means, coacting with said cutting and pointing means, forswaging the trailing end of the strip to form a head thereon and providea complete fastener, said cutting and pointing means being operated bythe hammer to drive the headed fastener from the tool and into the work.

2. A fluid pressure operated tool for making and driving fastenerscomprising means for holding a supply of wire; means for advancing thewire in predetermined increments; means for' severing the wire angularlyto provide strips having pointed ends; means for holding the strips asthey are cut individually from the supply; means, coacting with saidholding means and cutting means to form heads on the trailing ends ofthe strips to provide fasteners; means for driving the fasteners fromthe tool and into the work; a casing for enclosing the several abovenamed means;

and a fluid pressure operated plunger, reciprocable within the casing,said plunger having means for actuating the wire-advancing, severing,heading and driving means.

3. A fluid pressure operated tool for making and driving nailscomprising a casing provided with a bore; means for holding a supply ofwire on the casing; a fluid pressure operated plunger reciprocable inthe bore; means operated by and movable with the plunger for feedingwire from the supply during movement of the plunger in one direction andreleased from the wire when the plunger is moved in the oppositedirection; a hammer slidable in the bore; means operated by the hammerfor angularly severing the fed wire' in strips of predetermined lengthand pointing the leading end of successive strips; and means coactingwith and operated by the severing means for heading the trailing ends ofthe strips to form complete fasteners, said severing means beingoperated by the hammer to drive the fasteners individually from the tooland into the Work.

4. A fluid pressure operated nail making and driving tool comprising acasing having a bore; means for holding a supply of wire on the casing;a plunger reciprocable in the bore; means for admitting fluid underpressure into the bore to I feeding it forwardly; a hammer actuated bythe plunger; means actuated by the hammer for simultaneously severing astrip from the advanced wire and pointing the leading end of thesuccessive strip; and means, coacting with the severing means, forswaging the opposite end of the strip to form a head on the wire;further sliding movement of the severing means causing it to drive thenail from the tool and into the work.

5. A fluid pressure operated nail forming and driving tool comprising acasing having a bore; a plunger within the bore; means for selectivelyadmitting fluid under pressure to either end of the bore to move theplunger in opposite directions; means for holding a supply of wire onthe casing with its leading end positioned within the bore; meansactuated by the plunger for feeding the wire from the supply; means foradjusting the stroke of the plunger to control the length of wire fedforwardly; means for holding the fed length of wire; a hammer actuatedby the plunger; cutters, actuated by the hammer, fcr severing a strip ofwire from the fed length; means for pivoting said cutters as they areslid longitudinally to form a point on the leading end of eachsuccessive wire strip, said cutters coacting with the wire holding meansto form a head on the trailing end of the strip to complete theformation of a nail; and to finally drive the nail into the work; andmeans for guiding the nail during the driving operation.

6. A portable fluid pressure operated nail making and driving toolcomprising a casing formed with a bore: a plungerv' i-thin the bore;means for selectively admitting fluid under pressure to the ends of thebore to move the plunger in either direction; a manually-operable valvefor controlling the flow of fluid to the bore; means for holding asupply of wire on the casing; pivoted jaws, actuated by the plunger andengageable with the wire leading into the bore; said jaws being adaptedto feed the wire when the plunger is moved forwardly; means foradjusting the stroke of the plunger to control the length of Wire fedforwardly; a hammer actuated by the plunger; pivoted cutters operated bythe hammer to sever a strip of wire from the advanced length, saidcutters acting to point the leading end of each successive strip duringthe severing operation; and means, co-operating with the cutting means,for forming the trailing end of each strip into a head to complete theformation of a nail, said cutting means being operative to drive thenail into the work following its formation.

7. A portable fluid pressure operated nail making and driving toolcomprising a casing formed with a bore: a plunger reciprocable in thebore; means for admitting fluid under pressure to the ends of the boreto move the plunger in either direction; means for holding a supply ofwire on the casing with its leading end arranged within the bore; ahammer slidable in the bore; jaws pivoted on the hammer and forming adriving connection between the plunger and hammer, said jaws beingengageable with the wire to feed the latter when the plunger is movedforwardly; means for adjusting the stroke of the plunger to vary thelength of wire advanced; jaws pivoted within the casing for holding thelength of wire advanced, said holding jaws being provided with recesses;means actuated by the hammer for simultaneously severing successive wirestrips of predetermined length after pointing their leading ends, saidmeans forcing their trailing ends into recesses of the holding jaws toupset a head thereon and subsequently driving the completed nail intoand means for guiding the nail during the driving operation.

8. A portable fluid pressure operated nail making and driving toolcomprising a casing formed with a bore; a plunger reciprocable withinthe bore; means for admitting fluid under pressure to the ends of thebore to move the plunger in either direction; means for holding a supplof wire on the casing with its leading end arranged within the bore; ahammer slidable within the bore; means on the hammer interconnectedbetween the hammer and plunger for feeding the wire forwardly; means foradjusting the stroke of the plunger; a plurality of floating cutterswithin the casing actuated by movement of the hammer; recessed jawspivoted within the casing for holding the advanced length of wire; cammeans for pivoting the cutters during the forward stroke of the hammerto cause them to simultaneously sever and point successive strips ofwire, said cutters coacting with the holding jaws to swage the trailingend of each strip into the recesses thereof to form a complete nail andadapted to thereafter drive the nail into the work; and a plurality ofpivoted members within the casing for guiding the nail during thedriving operation and releasing the nail after its pointed end haspenetrated into the work.

9. A power operated tool for forming and driving wire nails comprising acasing having a longitudinal bore; means attached to the casing forholding a supply of wire, a plunger slidable within the bore; a hammeralso slidable within the bore and formed with a recessed end; wirefeeding elements pivoted on the opposite end of the hammer andengageable with the plunger to connect the hammer for actuation by theplunger, said elements being adapted to grip and feed a length of wireforwardly within the casing; a plurality of pivoted cutters movablelongitudinally within the bore, said cutters being provided at one endwith means engageable in the recess of the hammer during part of theslidin movement of the latter and with inclined cutting edges at theiropposite end; resilient means for normally holding the cutters in openrelationship to permit the wire to be fed forwardly between the cuttingedges; a cam formation within the casing for pivoting the cutters duringtheir forward movement to cause their inclined ends to simultaneouslysever a strip from the advanced wire and point the leading end of thesuccessive strip; a plurality of elements pivoted within the casing andoperated by the inclined ends of the cutters to grip and hold theleading portion of the advanced wire during the cutting operation, saidholding elements co-operating with the cutters during furtherlongitudinal movements of the latter to upset the trailing end of thestrip to form a head, thus making a complete nail; means for pivotingthe elements in the opposite direction, following the nail formingoperation, to cause them to release the nail; and a plurality ofelements pivoted within the casing for guiding the nail during thedriving of the latter into the work by the cutters.

10. A power operated tool for forming and driving fasteners comprising acasing having a longitudinal bore; means attached to the casing forholding a supply of wire; a plunger slidable in said bore; a hammer alsoslidable in the bore and formed with a recessed end; wire feedingelements pivoted on the opposite end of the hammer and engageable inopenings in the plunger to connect the hammer for actuation by theplunger, said elements acting to feed a length of wire forwardly withinthe casing; means for adjusting the stroke of the plunger topredeterminately control the length of wire fed by the elements; aplurality of cutters pivotally joined together to form a unit slidablewithin the bore, said cutters being provided with means at one endengageable in the recess of the hammer during part of the stroke of thelatter and with inclined cutting edges at their opposite ends; a springfor normally holding the cutters open to permit the wire to be fedforwardly betweentheir cutting edges; a plurality of angular elementspivoted within the casing and formed with co- 11 operating serratededges for gripping and holding the length of wire advanced by thefeeding elements, said holding elements being operated by the inclinedends of the cutting means during the cutting operation; a cam,stationary within the casing, engageable with the inclined ends of thecutters during the forward sliding movement of the latter to cause theircutting edges to move inwardly toward one another to simultaneouslysever a strip from the advanced wire and point the leading end of thesuccessive strip; longitudinal openings in the cutters, said cuttersbeing movable beyond the cutting position and relative to the wire stripheld by the holding elements to swage the trailing end of the strip thusforming a head thereon and to thereafter pivot the holding elements withportions thereof entering the openings in the cutters thus releasing theformed nail; and a plurality of elements pivoted in the casing andco-operating to form a guideway therebetween through which the nail isThe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 626,755 Frechette June 13, 1899675,926 Blott June 11, 1901 1,363,357 Saunders Dec. 28, 1920 1,562,547Farley Nov. 24, 1925 2,036,988 Ajouelo Apr. '7, 1936 367,282 Evans July26, 1887 1,246,070 Duckworth Nov. 13, 1917 1,484,150 Parks Feb. 19, 1924

